Messages in this thread | | | Date | Wed, 26 Mar 2014 18:10:07 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [PATCH 12/14] hrtimer: don't emulate notifier call to initialize timer base |
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On 03/26/2014 04:51 PM, Viresh Kumar wrote: > In hrtimers_init() we need to call init_hrtimers_cpu() for boot CPU. For this, > currently we are emulating a call to hotplug notifier. Probably this was done > initially to get rid of code redundancy. But this sequence always called a > single routine, i.e. init_hrtimers_cpu(), and so calling that routine directly > would be better. This would get rid of emulating a notifier call, few typecasts > and the extra steps we are doing in notifier callback. > > So, this patch calls init_hrtimers_cpu() directly from hrtimers_init(). >
I don't think this is such a good idea. Open-coding a part of that callback in the init routine can lead to loop-holes down the road: what if someone changes or adds something to the CPU_UP_PREPARE switch-case, and forgets to do the same in the init-routine?
It is more comforting to know that there is just one single place where CPU hotplug operations are handled (hrtimer_cpu_notify). That, in turn is good for reliability because it makes it easier to write bug-free code.
Regards, Srivatsa S. Bhat
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > kernel/hrtimer.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c > index f14d861..39dbdbd 100644 > --- a/kernel/hrtimer.c > +++ b/kernel/hrtimer.c > @@ -1756,8 +1756,7 @@ static struct notifier_block hrtimers_nb = { > > void __init hrtimers_init(void) > { > - hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE, > - (void *)(long)smp_processor_id()); > + init_hrtimers_cpu(smp_processor_id()); > register_cpu_notifier(&hrtimers_nb); > #ifdef CONFIG_HIGH_RES_TIMERS > open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq); >
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